Atrial Fibrillation Detection With an Analog Smartwatch: Prospective Clinical Study and Algorithm Validation.

BACKGROUND: Atrial fibrillation affects approximately 4% of the world's population and is one of the major causes of stroke, heart failure, sudden death, and cardiovascular morbidity. It can be difficult to diagnose when asymptomatic or in the paroxysmal stage, and its natural history is not well understood. New wearables and connected devices offer an opportunity to improve on this situation. OBJECTIVE: We aimed to validate an algorithm for the automatic detection of atrial fibrillation from a single-lead electrocardiogram taken with a smartwatch. METHODS: Eligible patients were recruited from 4 sites in Paris, France. Electrocardiograms (12-lead reference and single lead) were captured simultaneously. The electrocardiograms were reviewed by independent, blinded board-certified cardiologists. The sensitivity and specificity of the algorithm to detect atrial fibrillation and normal sinus rhythm were calculated. The quality of single-lead electrocardiograms (visibility and polarity of waves, interval durations, heart rate) was assessed in comparison with the gold standard (12-lead electrocardiogram). RESULTS: A total of 262 patients (atrial fibrillation: n=100, age: mean 74.3 years, SD 12.3; normal sinus rhythm: n=113, age: 61.8 years, SD 14.3; other arrhythmia: n=45, 66.9 years, SD 15.2; unreadable electrocardiograms: n=4) were included in the final analysis; 6.9% (18/262) were classified as Noise by the algorithm. Excluding other arrhythmias and Noise, the sensitivity for atrial fibrillation detection was 0.963 (95% CI lower bound 0.894), and the specificity was 1.000 (95% CI lower bound 0.967). Visibility and polarity accuracies were similar (1-lead electrocardiogram: P waves: 96.9%, QRS complexes: 99.2%, T waves: 91.2%; 12-lead electrocardiogram: P waves: 100%, QRS complexes: 98.8%, T waves: 99.5%). P-wave visibility accuracy was 99% (99/100) for patients with atrial fibrillation and 95.7% (155/162) for patients with normal sinus rhythm, other arrhythmias, and unreadable electrocardiograms. The absolute values of the mean differences in PR duration and QRS width were <3 ms, and more than 97% were <40 ms. The mean difference between the heart rates from the 1-lead electrocardiogram calculated by the algorithm and those calculated by cardiologists was 0.55 bpm. CONCLUSIONS: The algorithm demonstrated great diagnostic performance for atrial fibrillation detection. The smartwatch's single-lead electrocardiogram also demonstrated good quality for physician use in daily routine care. TRIAL REGISTRATION: ClinicalTrials.gov NCT04351386; http://clinicaltrials.gov/ct2/show/NCT04351386.

Determinants of regurgitant volume in mitral regurgitation: contrasting effect of similar effective regurgitant orifice area in functional and organic mitral regurgitation.

BACKGROUND: Quantitative assessment of the severity of mitral regurgitation (MR) is based on the calculation of the effective regurgitant orifice (ERO), a measure of lesion severity, and of the regurgitant volume (RVol), a measure of left ventricular volume overload. We aimed at evaluating the determinants of RVol in both organic (OMR) and functional mitral regurgitation (FMR). METHODS AND RESULTS: MR severity was quantitatively assessed using the proximal isovelocity surface area (PISA) method in 240 patients, 142 with OMR and 98 patients with FMR. By definition, ERO and RVol were strongly correlated both in patients with OMR and FMR (both R = 0.90, P < 0.0001) but the slopes of the regression lines were significantly different (P < 0.0001). This difference remained significant in patients with elevated systolic pulmonary artery pressure (SPAP > 40 mmHg, P < 0.0001) but not in patients with normal SPAP (≤40 mmHg, P = 0.09). In multivariate analysis, independent determinants of RVol were ERO (P < 0.0001), MR mechanism (FMR/OMR) (P = 0.0003) and SPAP (P = 0.03). In patients with elevated SPAP, ERO (P < 0.0001), left ventricular ejection fraction (LVEF) (P = 0.03), and MR mechanism (P = 0.03) were independently associated with RVol, whereas in patients with normal SPAP, ERO (P < 0.0001) was the only independent determinant of RVol. CONCLUSION: In the present study, we evaluated the contrasting effect of similar lesion severity in OMR and FMR and showed that similar ERO were associated with lower RVol in FMR compared with OMR. The regurgitant volume is the result of complex interactions of anatomic lesions, LVEF, and SPAP and our results highlight the importance of taking into account these parameters when interpreting RVol values in clinical practice, especially in FMR.

Comparison of real-time three-dimensional speckle tracking to magnetic resonance imaging in patients with coronary heart disease.

This study compared strain values from 2-dimensional (2D) and real-time 3-dimensional (3D) speckle tracking with hyperenhancement transmural extent by magnetic resonance imaging (MRI). The study included 18 control subjects (mean age 51 ± 10 years) and 25 patients (20 men, mean age 62 ± 16 years) with ischemic left ventricular (LV) dysfunction (mean LV ejection fraction 41 ± 9%) referred for viability assessment using MRI. Longitudinal, radial, and circumferential strain values were computed using 2D speckle tracking. From analysis of 3D speckle tracking, conventional strain markers (longitudinal, radial, and circumferential) and 2 new 3D strain indexes (area and 3D strains) were obtained from apical view 3D datasets. A hyperenhancement transmural extent segment (16-segment model) was defined as delayed contrast enhancement >50%. Overall, 661 of 688 segments (96%) were analyzable by MRI and 3D speckle tracking. All 3D strain components in hyperenhancement transmural extent segments (n = 154) were lower than in nontransmural necrosis (n = 219) and control (n = 288) segments. Longitudinal strain by 3D, but not by 2D, differentiated nontransmural segments with scar <25%. All 3D global strain indexes correlated with LV ejection fraction (r(2) = 0.67 to 0.26, p <0.05 for all comparisons), whereas only area, longitudinal, and circumferential 3D strains correlated with global scar extent. The best reproducibility was provided by 3D longitudinal (6%) and area (8%) strains. In conclusion, longitudinal and area strains by 3D speckle tracking provide an accurate and reproducible measurement of myocardial deformation that correlate with infarct size in patients with ischemic LV dysfunction.

Prognostic significance and normal values of 2D strain to assess right ventricular systolic function in chronic heart failure.

BACKGROUND: Normal values and the prognostic significance of right ventricle (RV)-2D strain in chronic heart failure (CHF) patients are unknown. METHODS AND RESULTS: Between 2005 and 2010, we prospectively enrolled 43 controls and 118 stable CHF patients. Standard echocardiographic variables, tricuspid annular plane systolic excursion, peak systolic velocity of tricuspid annular motion using tissue Doppler imaging, and RV and left ventricle (LV) 2D-strain were measured. The primary outcome was death or emergency transplantation or emergency ventricular assist device implantation or acute heart failure. RV-2D strain was measurable in 39 controls (58±17 years, 50% men), whose median value was 30% (95% confidence interval [95%CI], 39%; 20%); and in 104 CHF patients (80% men, mean age 57±11 years, and mean LV ejection fraction 29%±8%), whose median value was 19% (95%CI, 34%; 9%). During the mean follow-up of 37±14 months, 44 experienced the primary outcome. By Cox proportional hazards multivariate analysis, only RV-2D strain and log B-type natriuretic peptide independently predicted experiencing the primary outcome within the first year. The best RV-2D strain cut-off by receiver-operating characteristics analysis was 21%, and patients with values >21% were at greatest risk (χ(2)-log-rank test=14.1, P<0.0001). CONCLUSIONS: RV-2D strain is a strong independent predictor of severe adverse events in patients with CHF and may be superior to other systolic RV or LV echocardiographic variables.

Impact of acoustic window on accuracy of longitudinal global strain: a comparison study to cardiac magnetic resonance.

AIMS: To evaluate the impact of acoustic window on the feasibility and accuracy of longitudinal global strain (global-ε) by speckle tracking for assessing left ventricular (LV) systolic function. METHODS AND RESULTS: The study included 70 patients (57 ± 17 years, 64% men), 28 selected patients with a suboptimal image quality (IQ) defined by three or more segments (4 ± 3 segments/patient) with wall motion score not analysable visually and 42 patients with an optimal two-dimensional (2D) echocardiography IQ. Left ventricular ejection fraction (LVEF) by Simpson's biplane method (2D-EF), global-ε by speckle tracking, and peak systolic mitral annulus velocity [systolic tissue Doppler imaging (S-TDI)] were compared with LVEF by cardiac magnetic resonance (EF-CMR; 45 ± 18%, range 9-76%). Speckle-tracking analysis was feasible in all segments with an optimal acoustic window and in 85% (103/121) of segments poorly visualized. Global-ε similarly correlated with LVEF by CMR in patients with and without optimal IQ (r = 0.81 vs. 0.82 for good vs. poor IQ). In contrast, 2D-EF (r = 0.76) and S-TDI (r = 0.64) less correlated with LVEF by CMR in patients with a suboptimal IQ. Importantly, IQ only impacted on 2D-EF inter-observer reproducibility (9 ± 5 vs. 24 ± 22% for good vs. poor IQ) but not on global-ε reproducibility (9 ± 1 vs. 8 ± 7% for good vs. poor IQ). CONCLUSION: In patients with a limited acoustic window, longitudinal strain by speckle tracking remains accurate and reproducible for assessing global and regional LV systolic function.

Single-beat versus multibeat real-time 3D echocardiography for assessing left ventricular volumes and ejection fraction: a comparison study with cardiac magnetic resonance.

BACKGROUND: Real-time 3-dimensional echocardiography (RT3DE) is superior to 2D echocardiography in assessing left ventricular (LV) volumes and ejection fraction (EF), but its feasibility is limited by multibeat acquisition, which requires an optimal breath-hold and a regular heart rhythm. We sought to evaluate the accuracy and feasibility of single- and 2-beat RT3DE for LV volume and EF assessment. METHODS AND RESULTS: Sixty-six consecutive patients referred for cardiac magnetic resonance (CMR) underwent RT3DE and CMR on the same day. Of the 50 patients (age, 59+/-18 years; 68%men; 42% coronary artery disease; LVEF=49+/-14%; limits, 14% to 76%) with an adequate RT3DE image quality, accuracy for LV volumes and EF measurements of single- and 2-beat modalities were compared with the conventional 4-beat acquisition and CMR. Correlations with CMR for LV end-diastolic volume (161+/-59 mL, r=0.93 to 0.94) and end-systolic volume (86+/-56 mL, r=0.93 to 0.96) were excellent regardless of the number of cardiac cycles used. However, because of the low temporal resolution (7+/-2 volumes per second), single-beat underestimated LVEF (bias, -5+/-8%) with greater bias than 2-beat (bias, 1+/-6%, P<0.001) and 4-beat (bias, 3+/-7%, P<0.001) modalities. Interestingly, 2-beat provided accuracy similar to 4-beat for end-diastolic volume (bias, -17+/-21 mL versus -15+/-23 mL), end-systolic volume (bias, -9+/-16 mL versus -12+/-17 mL), and LVEF (bias, 1+/-6% versus 3+/-7%) measurements, but fewer stitching artifacts were observed with 2- than 4-beat modalities (3% versus 30%). CONCLUSIONS: Compared with conventional multibeat acquisitions, 2-beat modality provides similar accuracy in LV volume and EF measurements and should be preferred due to fewer stitching artifacts. In contrast, the temporal resolution of single-beat modality appears insufficient to provide an accurate estimation of LVEF.

Impact of longitudinal myocardial deformation on the prognosis of chronic heart failure patients.

BACKGROUND: Longitudinal myocardial deformation indexes appear superior to left ventricular ejection fraction (LVEF) in assessing myocardial contractility. However, few studies have addressed the prognostic value of longitudinal motion markers (velocity, strain, and strain rate) in predicting outcome in heart failure patients. METHODS AND RESULTS: The study included 125 consecutive symptomatic heart failure patients (63+/-16 years, 77% male, LVEF=31+/-10%). All patients underwent a complete echocardiographic and clinical examination, and brain natriuretic peptide level was assessed in 93 patients. Longitudinal myocardial velocity by tissue Doppler imaging, global-epsilon, and strain rate by speckle tracking were computed from apical views (4-, 3-, and 2-chambers views) and compared with the occurrence of major adverse cardiac events. On the whole, peak longitudinal velocity, global-epsilon, and strain rate averaged 5+/-2 cm/s (range, 1 to 9), -8+/-3% (range, -3 to -18), and -0.33+/-0.16 s(-1) (range, -0.83 to -0.05), respectively. During the follow-up period (266+/-177 days), major adverse cardiac events occurred in 47 (38%) patients (15 deaths, 29 recurrent heart failure, and 4 heart transplantations). By univariable analysis using Cox model global-epsilon, strain rate, and LVEF were associated with the occurrence of major adverse cardiac events, whereas only global-epsilon remained independently predictive of outcome by multivariate analysis. CONCLUSIONS: In the heart failure population, longitudinal global strain by speckle tracking is superior to LVEF and other longitudinal markers in identifying patients with poor outcome.

Usefulness of trans-oesophageal echocardiography using intracardiac echography probe in guiding patent foramen ovale percutaneous closure.

AIMS: To evaluate the use of intracardiac echocardiography probe through oesophageal route (ICE-TEE) for the monitoring of percutaneous foramen ovale (PFO) closure procedure. METHODS AND RESULTS: The study was conducted in 50 patients divided into two groups: in group I (n = 24), accuracy of ICE-TEE in assessing the inter-atrial septum (IAS) was compared with standard TEE, and in group II, we used ICE-TEE to monitor 26 consecutive patients referred for PFO closure. In group I, IAS was constantly visualized with a close correlation between ICE-TEE and standard TEE for IAS excursion (r = 0.9, P < 0.0001). In group II, ICE-TEE allowed to rule out four patients (three without PFO and one with septal atrial defect associated) and identified three complications during PFO closure procedure (pericardial effusion, inadequate device deployment, and cardiac thrombus). Finally, device implantation was successfully performed in the 22 patients with no residual shunt and thrombus observed after 3 months. CONCLUSION: ICE-TEE could be used to monitor PFO closure procedure.